Signals/Slots: GUI + Plugin Interface (API)

fem_dev

Hi, I would like to connect my UI Form Button to a Plugin API class slot function...but I got some Qt IDE erros:
My plugin class is called "Analysis X":

class ANALYSIS_XSHARED_EXPORT Analysis_x: public QObject, public Plugin_API
{
    Q_OBJECT
    Q_PLUGIN_METADATA(IID "com.lamar.plugin")
    Q_INTERFACES(Plugin_API)
 
public:
    explicit Analysis_x(QObject* parent = nullptr);
    ~Analysis_x() override;
 
    void run(void) override;
 
private:
    Form* _form;
 
public slots:
    void onMessage(QString msg);
};

My plugin GUI is a Form Class:

class Form : public QWidget
{
    Q_OBJECT
 
public:
    explicit Form(QWidget *parent = nullptr);
    ~Form();
 
signals:
    void mySignal(QString msg);
 
private slots:
    void on_save_btn_clicked();
 
private:
    Ui::Form *ui;
};

So, I tried to connect both using:


void Analysis_x::run()
{
    qInfo() << "RUNNING: analysis X";
    _form = new Form();
    _form->show();
    _form->connect(&_form, &_form->mySignal, &this, &this->onMessage);
}

But I got this errors:

analysis_x.cpp:62:28: error: cannot create a non-constant pointer to member function
analysis_x.cpp:62:46: error: cannot take the address of an rvalue of type 'Analysis_x *'
analysis_x.cpp:62:53: error: cannot create a non-constant pointer to member function

What I have to do to connect these QObjects?

fem_dev

@mrjj perfect! Thank you! You are great!

mrjj

@fem_dev said in Signals/Slots: GUI + Plugin Interface (API):

_form->connect(&_form, &_form->mySignal, &this, &this->onMessage);

The syntax is more like
_form->connect(_form, &Form::mySignal, this, this->onMessage);
Too many & and you must use the class name and not the instance for the function pointer.

fem_dev

@mrjj said in Signals/Slots: GUI + Plugin Interface (API):

_form->connect(_form, &Form::mySignal, this, this->onMessage);

I tried it now, but I got:

analysis_x.cpp:63:56: error: reference to non-static member function must be called

mrjj

Hi
did you use the keyword static in any place ?
als do you have the body defined for
void onMessage(QString msg);

else check the syntax again
https://wiki.qt.io/New_Signal_Slot_Syntax

Update:
sorry, too hot.
The last part is also incorrect

_form->connect(_form, &Form::mySignal, this, &Analysis_x::onMessage);

fem_dev

@mrjj
No, I don't use the keyword static in any place.

I defined void onMessage(QString msg); because I'm sending a message from a clicked button to my Plugin API:

My Signal implemetation:

void Form::on_save_btn_clicked()
{
    emit mySignal("Save");
}

My Slot implementation:

void Analysis_x::onMessage(QString msg)
{
    qInfo() << "My msg: " << msg;
}

What I'm doing wrong?

mrjj

@fem_dev
hi you are mixing old and new syntax :)
try
form->connect(_form, &Form::mySignal, this, &Analysis_x::onMessage);

fem_dev

@mrjj perfect! Thank you! You are great!